Digital information apparatuses in recent years, especially, recording/playback apparatuses such as digital still cameras, digital video cameras, and the like, which record images and audio information, require large-capacity storage media in terms of the characteristics of information to be handled. In digital still cameras, the number of image sensing pixels increases dramatically year by year, and the recording data size is still on the rise. In the field of video cameras, the recording data size is increasing upon transition from the SD format to the HD format.
Upon an increase in the data size to be handled, large-capacity recording media (memory cards) are in high demand, and the capacity of the recording medium itself is expected to maintain the increasing trend. Under the circumstances, media which have a capacity beyond the maximum recording capacity assumed in the conventional area format the recording area format of recording media have been developed, and media must be initialized by a new area format.
For example, a CF card used in digital cameras and the like is generally formatted by a file system called FAT (File Allocation Tables) 16 (or simply FAT). In the specification of the FAT16 file system, the maximum size per cluster is specified by 32 KB. Since such clusters are accessed by 16-bit addresses, 32 KB×216=2 GB (gigabytes), and a memory space up to 2 GB in maximum can be accessed. In other words, an area beyond 2 GB cannot be accessed.
However, the memory card vendors have released 4 GB micro drives. Since the conventional FAT16 does not support such large-capacity storage media, a further extended file system, e.g., FAT32, must be used.
The trouble is that conventional digital devices that assume to handle storage media formatted by the FAT16 file system (most of not only existing digital cameras but also conventional photo-direct printers which print by mounting storage media) can digitally connect storage media but cannot access files stored in the FAT32 file system.
Under the circumstance, two different file systems, i.e., FAT16 and FAT32, may be used together. As a technique that allows multiple recording in two, old and new file formats on a single storage medium, for example, Japanese Patent Laid-Open No. 8-63901 (to be referred to as reference 1) and Japanese Patent Laid-Open No. 8-153376 (to be referred to as reference 2) are known.
Reference 1 mainly aims at recording high-quality data while maintaining the compatibility of the CD-DA format in consideration of the software market. That is, this technique records audio data (sampling frequency=44.1 kHz and quantization bit rate=16 bits) concentrically from the inner to the outer periphery of a disk, and records high-quality data with a higher bit rate or sampling rate on the remaining area.
In case of rewritable recording media for digital information devices such as digital still cameras and the like, data may be changed as needed. For this reason, when data are multiplexed and recorded on a plurality of recording areas, the data relationship may become inconsistent unless link information for respective recording data is available.
For example, if unnecessary data exist, and data in only one area is erased, unnecessary data remains in the other recording area. Since the multiplexed data are mutually related, if one data is erased, the other data is preferably erased except for a special case such as backup or the like.
However, since reference 1 above does not define association of data recorded on respective recording areas, it is difficult to rewrite data as needed once recording is complete for the aforementioned reason.
An “image handling apparatus” proposed by reference 2 does not consider any image recording control when a single recording medium includes a plurality of formats. For this reason, if a plurality of formats exist in a single recording medium, the user must select which format is to be used, resulting in troublesome operations.
When the free capacity of the currently used format becomes small, a required number of photos cannot be recorded in a continuous shot mode or moving image recording is interrupted although a sufficient free capacity still remains in the recording medium.
In general, a removable medium stores information for respective clusters. One cluster is a group of a plurality of sectors. The cluster size changes depending on the file system and media size. Since a cluster is a minimum unit required to handle a file, even data smaller than one cluster size uses one cluster area if it is stored as a file. For this reason, when the number of files stored in one removable medium increases, the total size of wasteful areas increases, and the full storage size of the removable medium cannot be effectively used. In other words, if one cluster size is small, the size which is consumed wastefully becomes small, and the recordable size can be increased.
On the other hand, in case of a series of large data such as a moving image, since the number of clusters that form a file decreases with increasing cluster size if the file sizes remain the same, the access count to clusters decreases, and the access speed can be increased. For these reasons, the data size (or cluster size) and access speed have a tradeoff relationship each other.
A method that allows the user to change an optimal format of a removable medium to increase the access speed of the medium is known (e.g., Japanese Patent Laid-Open No. 11-112937). Furthermore, a method that allows the user to select whether an importance is attached to the size or access speed upon initializing the format of a removable medium is known (e.g., Japanese Patent Laid-Open No. 2004-80461).
However, when a removable medium is used in an image sensing apparatus such as a digital camera, digital video camera, or the like, the first formatting determines the subsequent properties, and the properties of images to be recorded cannot be adaptively supported under existing circumstances.